A liquid ring vacuum pump or compressor apparatus includes a rotor mounted for rotation within a pump housing, with vanes extending generally radially forming a plurality of working chambers. A port-containing cone member has a large base end and an opposite small end, the cone member having sequentially an inlet segment, a compression segment, a discharge segment, and a seal segment. A pumped gaseous medium is admitted to and discharged from the working chambers through the ports in the cone. Two such cones are preferably mounted small end to small end within the housing to form a double-cone pump. Liquid ring vacuum pumps, as exemplified by Roe et al U.S. Reissue Pat. No. 29,747, which is incorporated herein by reference, use "seal water" to form a liquid ring of pumping chambers that compress the gas and push it out of the pump, and to form a seal between high pressure gas being discharged and low pressure gas entering the pump. This seal is formed in the angular land area segment of the 360 degree cycle, where the liquid ring pistons contact the cone surface. As used herein, the land, land area, land segment, or seal segment of the cone shall mean the portion of the cone which is in closest communication with the working water pistons. The efficiency of the pump depends on the seal created by both the radial clearance of the metal surfaces of the rotor vanes and cone surface and the liquid pistons contacting the cone land area.
Metal parts of a liquid ring pump, particularly the rotor vane inner tapered surfaces and the land area of the cone, have a critical radial clearance in manufacture to achieve maximum efficiency in operation. In the past, this critical clearance has been the same in all four segments of the cone surface.
The sealing liquid in the pump is required in the land area segment of the cone between the rotor blades and the land area surface to prevent the high pressure discharge gas from bypassing the gas outlet and recirculating to the inlet segment of the pump, thereby avoiding reducing the volume of gas displacement and the efficiency of the pump. Sealing water is not needed between the rotor blades and cone surface in the other three segments of the cone, namely; inlet, compression, and discharge, except at the smaller diameter of the cone. In these three segments, working pistons are needed to allow gas to fill between the rotor blades, to compress and discharge the gas through and out of the pump. Seal water is needed at the small diameter of the cone in all four segments of the cone.
In prior art designs, the cone surfaces have required careful machining in order that all surfaces meet a stringent straightness requirement. The same careful machining has also been required in the repair of a cone during the rebuilding of a pump.